Mao pointed out that risks caused by policies to maintain stable economic growth have emerged, including a high debt-to-GDP ratio, less effective stimulus policies and inefficient State-owned enterprises (SOEs) with high levels of debt.

He called for countermeasures to prevent a crisis such as debt restructuring by the government, SOEs and the private sector.

China's total debt-to-GDP ratio reached 254 percent as of March 2016 and the figure may reach 266 percent by the end of 2016, according to Mao.

Though market liquidity is improving, the velocity of money is falling, Mao said, noting that it takes 213 yuan ($30.95) in circulation to achieve 100 yuan worth of GDP growth, which could also indicate that stimulus policies are losing steam.

Another risk is the rise in the debt of SOEs, which could exacerbate default rates. Moody's Investors Service has forecast an increased risk of default in 2017 for some corporations, including SOEs, particularly those with weak performances.

Since China's first bond default in 2014, there have been 85 bond defaults involving more than 37 billion yuan, according to CCXI.

In 2014, about 2.6 trillion yuan worth of bonds matured, but the amount will rise to about 5 trillion yuan in 2017, increasing credit risks amid an environment of macroeconomic uncertainty, CCXI Managing Director Zhang Yingjie said. And that could cause some trouble for the banking sector and local governments.

"Special-mention" loans in the banking sector stood at 3.48 trillion yuan as of September 2016, increasing 24 percent year-on-year, data from CCXI showed.

Moody's said the banks' operating environment will become more challenging in the coming 12-18 months.

It also said the high leverage of SOEs is weighing on the credit quality of regional and local governments, driving its negative outlook for the sector over the next 12 to 18 months.